Mineral precipitation and the associated reduction of hydraulic conductivity in a PRB

Permeable reactive barriers (PRB) have been used worldwide for the in-situ treatment of con-taminated ground water. One such contamination found in Australia is acidic groundwater enriched with high concentrations of dissolved aluminium and iron produced in acid sulfate soil (ASS) terrains. To treat this acidi-ty in groundwater, a PRB was installed in the Shoalhaven Floodplain and then monitored over a seven year pe-riod. This remediation process was satisfactory but there was a small decrease in efficiency due to a secondary mineral precipitation (aluminium and iron oxy/hydroxides) which reduced the hydraulic conductivity of the PRB. Numerical modelling carried out through MODFLOW and RT3D software showed that this reduction in hydraulic conductivity due to secondary mineral precipitation was 3% at the entrance of the PRB after seven years of installation. This result was satisfactory considering that the predicted longevity of the barrier was 19.5 years, assuming a mean groundwater velocity of 0.05 m/day

Vulnerability Assessment for Climate-Induced Disasters in Malaysia.

Climate induced disasters can be considered as an outcome of a triggering agents (often known as the hazard) and vulnerability factors. Within the context of climate-induced disasters, humans do not have the control over the triggering agents. Even though it is difficult to control the triggering agent, the level of its exposure to a vulnerable community or system would determine the severity of its impact. Within this context, by reducing the vulnerability the impact of climate-induced disasters can be minimized. Accordingly, this study evaluates the disaster vulnerability factors in Malaysia with particular reference to the climate-induced disaster- floods. A workshop has been carried out with the involvement of practitioners and professionals who are linked with the disaster management activities to identify the key vulnerable factors from the context of Malaysia. The findings identified Social Vulnerability as the main vulnerability factor that affect the Malaysian community followed by Operational/Managerial, Technological, Economic and Political. The findings of the study revealed the need of addressing vulnerability factors at different levels such as at the community, institutional and policy levels and how the vulnerability factors are interconnected with one another